<?php

namespace Drupal\custom_forms\Form;

use Drupal\Core\Ajax\AjaxResponse;
use Drupal\Core\Ajax\CloseDialogCommand;
use Drupal\Core\Form\FormBase;
use Drupal\Core\Form\FormStateInterface;
use Drupal\Core\Url;
use Symfony\Component\HttpFoundation\Request;

/**
 * Class CustomFormItemFormBase
 *
 * Base class for the various forms used by custom form items, such as the
 * settings and states forms.
 *
 * @package Drupal\custom_forms\Form
 */
abstract class CustomFormItemFormBase extends FormBase {

  /**
   * Form constructor.
   *
   * @param array $form
   *   An associative array containing the structure of the form.
   * @param \Drupal\Core\Form\FormStateInterface $form_state
   *   The current state of the form.
   *
   * @return array
   *   The form structure.
   */
  public function buildForm(array $form, FormStateInterface $form_state) {
    $request      = \Drupal::request();
    $attributes   = $request->attributes;
    $customForm   = $attributes->get('custom_form');
    $settings     = \Drupal::config('custom_forms.settings');

    // Add the basic form actions.
    $form['actions'] = [
      '#type' => 'actions',
      '#weight' => 99,
    ];
    $form['actions']['save'] = [
      '#type' => 'submit',
      '#op' => 'submit',
      '#value' => $this->t('Save'),
      '#ajax' => [
        'callback' => [$this, 'ajaxSubmitForm']
      ],
      '#attributes' => [
        'class' => [
          'button',
          'button-action',
          'button--primary',
        ],
      ],
    ];

    $form['actions']['cancel'] = [
      '#type' => 'submit',
      '#op' => 'cancel',
      '#value' => $this->t('Cancel'),
      '#ajax' => [
        'callback' => [$this, 'ajaxCancelForm']
      ],
      '#attributes' => [
        'class' => [
          'button',
          'button-action',
          'button--secondary',
        ],
      ],
      '#limit_validation_errors' => [],
    ];

    // If the request is not XHR, we assume it's being rendered normally and
    // won't need the ajax submit and change the cancel button to a simple link.
    if (!$request->isXmlHttpRequest()) {
      unset($form['actions']['save']['#ajax']);

      $cancel_url = Url::fromRoute('entity.custom_form.fields_form', ['custom_form' => $customForm->id()], ['absolute' => FALSE]);

      $form['actions']['cancel'] = [
        '#type' => 'link',
        '#url' => $cancel_url,
        '#title' => $this->t('Cancel'),
        '#attributes' => [
          'class' => [
            'button',
            'button-action',
            'button--secondary',
          ],
        ],
        '#limit_validation_errors' => [],
      ];
    } else {
      // If the form is rendered via XHR, we add a warning message in case
      // the user has unsaved sorting/nesting changes to the field list.
      switch ($settings->get('off_screen_field_settings')) {
        case 'rebuild':
          $warning_message = $this->t('If you have any unsaved changes to the field list, these changes will be lost if this form is saved. <br>Unsaved chances could be anything from the order of the fields/groups to the nesting of them.');
          break;
        case 'reload':
          $warning_message = $this->t('When saving this form, the page itself will reload to update the changes. If the reload is interrupted the page might not work until a manual refresh is done.');
          break;
      }

      // If there is a warning message, we display it.
      if (!empty($warning_message)) {
        $form['warning'] = [
          '#theme' => 'status_messages',
          '#weight' => 100,
          '#message_list' => [
            'warning' => [
              $warning_message
            ]
          ],
          '#status_headings' => [
            'status' => $this->t('Status message'),
            'error' => $this->t('Error message'),
            'warning' => $this->t('Warning message')
          ]
        ];
      }
    }

    return $form;
  }

  /**
   * Handle submission through ajax.
   *
   * @param array $form
   *   The form render array.
   * @param \Drupal\Core\Form\FormStateInterface $form_state
   *   The form state object.
   * @param \Symfony\Component\HttpFoundation\Request $request
   *   The HTTP request.
   *
   * @return AjaxResponse
   */
  abstract function ajaxSubmitForm(array &$form, FormStateInterface $form_state, Request $request);

  /**
   * Handle cancelling the ajax form.
   *
   * @param array $form
   *   The form render array.
   * @param \Drupal\Core\Form\FormStateInterface $form_state
   *   The form state object.
   * @param \Symfony\Component\HttpFoundation\Request $request
   *   The HTTP request.
   *
   * @return \Drupal\Core\Ajax\AjaxResponse
   */
  public function ajaxCancelForm(array &$form, FormStateInterface $form_state, Request $request) {
    $response = new AjaxResponse();
    $response->addCommand(new CloseDialogCommand('#drupal-off-canvas'));
    return $response;
  }
}